4.1.4.2 Coated copper conductors4.1.4.2.1 Each tin-coated conductor shall comply with the requirements of ASTM B 33 orNMX-J-008-ANCE; each wire in a lead-alloy-coated wire shall comply with the requirements of ASTM B189; a nickel-coated wire shall comply with ASTM B 355 and a silver-coated wire shall comply with ASTMB 298. Conductors coated with other metals or alloys shall be subjected to special investigation.In Mexico, the use of lead-alloy-coated wires is not permitted.Note: In Mexico, the use of ASTM B 355 is recommended for nickel-coated wire, and the use of ASTM B 298 isrecommended for silver-coated wire.